Simulation at Two Different Levels of Complexity

1. A method of simulating a creature for use in two different complexities of simulation, the method comprising: utilizing a model of the creature that comprises at least two portions: a first portion which contains functions for use in both of said different complexities of simulation; and a second portion comprising two alternative versions: a first version for use in one of said different complexities of simulation, wherein the first version utilizes a neural network; and a second version for use in the other of said different complexities of simulation, wherein said first portion comprises a behavior selection mechanism arranged to select the behavior of said creature and said second portion is arranged to execute the selected behavior.

2. A method as claimed in claim 1 , wherein said behavior selection mechanism is arranged to select the behavior based upon at least one of: the current behavioral state; one or more internal state variables of the creature; the environment surrounding the creature; and one or more sensory inputs to said creature.

3. A method as claimed in claim 1 , wherein said behavior selection mechanism consists of a set of mutually exclusive behavioral states.

4. A method as claimed in claim 1 , wherein the second version is for use in a less complex of the simulations, and is arranged to approximate functionality of the first version.

5. A method as claimed in claim 1 , wherein the first version utilizes a three dimensional physical simulation of an animat, and the second version utilizes a parameterized model of the animat to approximate movement.

6. A method of simulating activities of a plurality of creatures, the method comprising utilizing at least two modes of simulation: a first mode arranged to simulate the activities of all of said creatures; and a second mode arranged to simulate an activity of at least one of said creatures at a more detailed computational level of complexity than said first mode, wherein a model of a creature simulated in both modes of simulation comprises at least two portions: a first portion which contains functions arranged for use in both of said first, second modes of simulation; and a second portion comprising two alternative versions, a first version for use in said first mode of simulation, and a second version for use in the second mode when selected for closer inspection of the at least one creature being simulated.

7. A method of simulating a process at two different levels of complexity, the method comprising: utilizing a model that comprises at least two portions: a first portion which contains functions for use in both of said two different complexities of simulation; and a second portion comprising two alternative versions: a first version for use in one of said two different levels of complexities of simulation when selected for closer inspection of the process being simulated; and a second version for use in the other of said different levels of complexities of simulation, wherein the second version is for use in a less complex level of the simulations, and is arranged to approximate functionality of the first version.

8. A method as claimed in claim 7 , further comprising evaluating one or more conditions to determine a result of a rule for selecting which of the two alternative versions of the second portion to use in simulating the process.

9. A method as claimed in claim 7 , wherein the first version utilizes a neural network.

10. A simulator device arranged to simulate a creature in two different levels of complexities of simulation, the simulator device being arranged to utilise a model of the creature that comprises at least two portions: a first portion which contains functions used in both of said two different levels of complexities of simulation; and a second portion comprising two alternative versions, a first version used in one of said two different levers of complexities of simulation when selected for closer inspection of the process being simulated, and second version used in the other of said different levels of complexities of simulation; wherein the second version is for use in a less complex of the simulations, and is arranged to approximate functionality of the first version.